Heretofore, the prior art has attempted to employ headbox structures with a plurality of distribution type pipes or conduits in the belief that a better quality of paper could thereby be achieved. That is, for example, the characteristic or quality of transparency of the paper can be enhanced if a uniform paper fiber distribution is achieved.
Prior art attempts at employing such headbox structures comprised of a plurality of distribution conduits or tubes have not been totally successful especially in situations where the pulp stock is comprised of long fibers. In those situations, the long fibers get caught or trapped as at the inlet or inlets of the distribution tubes and, in turn, cause an undesirable blockage, partial or total, to flow through the related distribution conduits which, of course, results in an uneven distribution of the pulp stock being fed. The prior art has attempted to overcome this problem by providing greater space between adjacent inlets to the distribution tubes or conduits; however, such has not successfully overcome the problem.
Federal Republic of Germany Letters Patent No. 2,007,308 which attempts to achieve uniformity of distribution and employs a plurality of discharge tubes or channels, has such discharge tubes or channels of straight configuration and situated as to have the respective flows exiting as from two adjacent discharge tubes passing in directions generally convergent thereby impinging upon each other in the hope that such impingement will result in somewhat a rebounding action of the pulp stock and that the fibers will be deposited in an even and uniform manner. However, such attempts have not proven to be successful.
In Federal Republic of Germany Publication No. AS-14-61-072 the use of a plurality of discharge tubes or conduits is also disclosed; however, in comparison to said Fed. Rep. of Germany Pat. No. 2,007,308, such discharge tubes, as in the general area of their respective discharge orifices, are parallel to each other thereby preventing the impingement of pulp stock flows sought in said German Pat. No. 2,007,308. Further, the discharge conduits of said Publication No. AS-14-61-072 are formed as to have generally oppositely directed dual bends which, of course, complicates fabrication and increases the costs thereof. This structure also has not proven to be totally successful in overcoming the problems of the prior art.
The headbox structure of Fed. Rep. of Germany Letters Patent No. 2,307,849 even though not providing completely satisfactory results nevertheless provides results superior to that obtainable as with the teachings of either said Fed. Rep. of Germany Letters Patent No. 2,007,308 or Publication No. AS-14-61-072. However, in those situations where the pulp stock has, for example, exceptionally long fibers, as may be used in the fabrication of cardboard, the structure of said German Pat. No. 2,307,849 becomes unsuitable because of the fact that such long fibers still tend to get stuck, accumulate and generally not be uniformly distributed.
The invention as herein disclosed and claimed is primarily directed to the solution of the aforestated and other related and attendant problems.